1. Field of the Invention
The present invention relates to a semiconductor device and a memory card using the same.
2. Description of the Related Art
Semiconductor memory cards having a NAND type flash memory or the like built therein are downsized while having larger capacity. For instance, SD (trademark) memory card is presented in three sizes, a size of a normal SD (trademark) card, a size of a mini SD (trademark) card and a size of a micro SD (trademark) card, in which even the micro SD (trademark) card is expected to have a larger capacity. In an attempt to increase the capacity of the downsized memory card, it is examined and put into practical use that the semiconductor device having a built-in semiconductor element such as a memory element, a controller element or the like forms the memory card without being accommodated in a case such as a base card.
In order to manufacture a small-sized memory card, a circuit board frame, in which regions to form a plurality of memory cards are arranged in a matrix manner, is prepared at first. An external connecting terminal is formed in each of the card-forming regions by electrolytic plating or the like, and after that a semiconductor element is mounted on a rear surface side. Subsequently, the semiconductor elements and the circuit boards are electrically connected and a sealing resin is formed by molding on the rear surface of the circuit board frame to seal the semiconductor elements mounted on the plurality of card-forming regions all at once.
The circuit board frame together with the sealing resin is cut in accordance with the card forming regions to manufacture the plurality of memory cards all at once. A cut-out portion, a constricted portion and the like indicating a head or rear direction and an upper or lower direction of the card when the card is equipped into a card slot is provided at an outer peripheral portion of the memory card. In the memory card formed by accommodating the semiconductor device in the case, the cut-out portion, the constricted portion and the like are formed at the case. In the memory card formed by the semiconductor device only without using the case, the cut-out portion, the constricted portion and the like need to be formed at the semiconductor device itself.
When cutting the circuit board frame, a blade dicing being highly speedy is adopted in general. Since the cut-out portion and the constricted portion have a complicated form including a curved portion, the adoption of a laser beam machining or a water jet machining is under consideration. However, these machining methods have a problem of a low cutting speed compared with the blade dicing. When the laser beam machining or the water jet machining is adopted to cut the entire outline, a machining efficiency down in the cutting step of the circuit board frame is unavoidable.
The curved portion needs to be cut at a lower speed than the speed to cut the linear portion, in which the machining efficiency downs further. Of the laser machining and the water jet machining effective for cutting the curved portion, the laser machining exhibits a higher cutting efficiency as compared to the water jet machining, whereas a cooling efficiency thereof downs at the time of a low-speed cutting, in which a problem of heat generation is caused at the cut portion. Affected by the heat generated at the time of the cutting, there arise problems such as an insulation performance down between the wirings, a short circuit caused by carbonized resist or core material composing the circuit board, and further an easily-caused characteristic degradation of the semiconductor element.